Previous known gas burners for cooking hobs are built by means of assembling three main components placed one on top of the other: a cup, constrained to the cooking hob and extending to some extent below the said hob, a central burner body, provided with, or functionally linked to, at least one annular chamber having as its lateral wall an annular flame diffuser, and a superior cover which usually defines the upper wall of the said annular chamber.
The burner cup, fluidically connected to the combustible gas supply by means of a flexible supply pipe, contains an injector for the said combustible gas, whereas the central body is usually fitted with a Venturi tube, possibly radial, designed to mix the combustible gas with the atmospheric air (primary air), taken from either above, or below the cooking hob. The cup and the burner body can be fixed together in a stable way, for example, by being bolted together, otherwise they can just be reciprocally juxtaposed, so as to make it easy for the burner body to be removed from the cup, as is for example necessary during maintenance operations to the burner.
The superior cover can also be mounted to the central burner body in a substantially non-removable way, by means of threaded elements, or alternatively in a removable way, by simply resting on it, to allow the central body to be cleaned and maintenance work to be carried out. There are also some known intermediary solutions, where the cover is fixed to the burner body in a transitory way, by means of a reversible mechanical coupling, for example, of the bayonet type, or in which the cover is reversibly constrained to the cup by elastic means (for example, a clip or elastic clamp), so as to hold the central burner body between the cover and the cup.
Such reversible solutions for fixing the cover can prove useful, above all, in vehicles, such as campers, caravans and boats, where having the cover simply rest on the central burner body may not be enough to stop the cover from becoming dislodged from the central burner body while the vehicle is moving, resulting in it damaging the cooking hob, or making it impossible to use the same burner; and where other solutions with the stable coupling between cover, body and cup results in complicated cleaning and maintenance operations of the said burner.
Moreover, being able to couple the cover only in a transitory way to the same central body, or to the cup of the same burner, as opposed to the other solutions, affords both easy partial maintenance of the outside of the burner, which does not require removal of the cover, and complete maintenance operations involving disassembling the entire burner.
The U.S. Pat. No. RE 22,877 (HARPER), concerning a burner with two concentric flame crowns, teaches to couple a cover, with an annular flame diffuser, and a burner body by means of inserting some fins, which the cover is provided with, in corresponding grooves provided in the burner body. The grooves have some widened portions which the fins can be inserted into and removed from, and some portions designed to hold said fins. By supplying the combustible mixture directly to the burner body and without it having to be flush-mounted into a cooking hob, the HARPER burner does not foresee, nor suggest, the use of a burner cup, and therefore it does not describe how to couple three or more components of the burner contemporaneously in a reversible way.
The French application for a patent FR 2.618.881, in the name of MADEC-MATER, describes a flush-mountable burner comprising a lower cup onto which are coupled one or more intermediate coaxial bodies, provided with a possible annular flame diffuser, and a superior cover that encloses the burner. The superior cover is fixed in a reversible way to the burner cup by means of a threaded pin (see FIG. 5 of the MADEC-MATER patent), whose head holds the cover, and whose foot is shaped so as to be locked in a releasable way inside special elastic holding means (clip), which said burner cup is provided with. The central burner body is further held down to the cover by means of a nut that is screwed onto the pin.
Even though the application FR 2.618.881 envisages the use of a burner comprising numerous parts placed one on top of the other, and held together by reversible fixing means, the use of elastic means for holding the shaped foot of the pin, nevertheless, entails complications during production and, by becoming permanently deformed with use, the elastic elements or clips may no longer be of use in holding the pin, giving rise to the diminished effectiveness of such reversible fixing means in time.
Furthermore, the MADEC-MATER patent does not envisage a loose coupling between the cover and the central burner body when the cover is disconnected from the cup, in this way forcing the user to loosen the nut to be able to separate these two elements during complete maintenance operations to the burner.
One purpose of the present invention is to provide a gas burner of the type comprising a lower cup, at least one central body, an annular flame diffuser, preferably integral to the central body, and a superior cover, interconnected each other by means of reversible fixing means, that is at the same time easy to produce, effective in its functioning and practical to use.
Another purpose of the present invention is that of providing a gas burner of the type described above, on whose internal, or only external parts the user can easily carry out maintenance operations.
A further purpose of the present invention is that of producing a gas burner that is suited to being fitted to a cooking hob installed in vehicles; that is safe to use and whose reversible fixing means do not present problems of reliability and effectiveness.